Improvement in lifting-jacks



dilated d/tane TIMOTHY SIEBINS, OF SAN FRANCISCO, CALIFORNIA. Lette/rs Patent No. 88,923, dated April 13, 1869.

IMPROVEMENT IN LIFTING-J'ACKS.

To all whom 'it may concern:

Be it known that I, TIMOTHY ScnnBrNs, of the city and county of San Francisco, State of California, have invented an Improved Lifting-Jack; and I do hereby declare the following description and accompanying drawings are sufficient to enable any person skilled in the art or science to which it most nearly appertains, to make and use my said invention or improvements without further invention or experiment.

The object of my invention is to provide an improved lifting-jack, so constructed that heavy weights may be either raised or gradually lowered, as desired, by the same movement of the lever, and this is accomplished by means of a pawl pivoted directly over the operating lever, having a curved projection at the end opposite that which operates in the rack.

A weighted arm is hinged to the arm of the lever, and is thrown over, so as to rest upon the curved projection, and by its weight free the pawl from the teeth, when it is desired to lower the rack, and by operating the lever the pawl is freed from each tooth by the weighted armat each down ward movement and caused to catch the next tooth above as the lever is raised, by the weighted arm striking a spring, made of rubber, or other suitable material attached to the lever, near its eentre.-

To more fully explain my invention, reference is had to the accompanying drawings, forminga part of this specification, which represent a side sectional elevation.

A is an upright frame, or guide, similar to that usually employed in lifting-jacks.

The lifting-slide B moves up and down in ways, and

lis provided with the usual rack.

Near the top of the frame,'and on each side, are lugs, a a, to which- 'the operating lever O'is hung by means of links, b b, as shown.

The end of the lever C is constructed so as to en gage the teeth of the rack.

Between the links b b, and pivoted near its middle, is a pawl, D, which engages the teeth of the rack as it is raised by the lever C. l

The opposite end, h., of this pawl is curved outward, and a spring, c, is attached near its middle.

In this situation, the pawl D acts similar to those generally used and engages the teeth consecutively as they are raised by the lever, the upper portion of the pawl being heavier than the lower.

When it is desired to lower the slide B, a weighted arm, E, which is hinged to the lever at d, is thrown over, so as to fall upon the curved or lower portion, h, of the pawl, and by the extra weight thus brought to bear upon that part, it raises the pawl from the rack at each downward movement of the lever, and as the lever is raised, the arm E striking the spring c, causes it to catch the tooth next above, and so on' lowering the slide at each movement.

A lug, g, projects upward from the arm of the lever, between the pawl and arm E, upon which the arm E rests, when the handle of the lever is raised suciently to free it from the curved end vh of the pawl.

Having thus described my invention,

What I claim, and desire to secure by Letters Patentis'- In a lifting-j ack, the weighted arm E, on the lever O, and the spring c, together with the pawl, having the curved end h, substantially as herein described.

In witness whereof, I have hereunto set my hand and seal.

Y TIMOTHY STEBINS. [1.. s]

.Witnesses:

Gno. H. STRONG, J. L. BOONE. 

